I use French notation for intervals, like
But the brackets behave funny --- they try to surround wrong thing, like
] x,y [∪] a,b [
\left]x,y\right[\cup\left]a,b\right[ solves the problem in most cases. But I want these brackets to have the same size, but they become larger on something like
P.S. My question is closely related to "How to input open intervals", but not the same.